/*
 * Copyright (c) 2002, 2003 Niels Provos <provos@citi.umich.edu>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef HAVE_CONFIG_H
#include <config.h>
#endif

#ifdef WIN32
#include <winsock2.h>
#include <windows.h>
#endif

#ifdef HAVE_VASPRINTF
/* If we have vasprintf, we need to define this before we include stdio.h. */
#define _GNU_SOURCE
#endif

#include <sys/types.h>

#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_STDARG_H
#include <stdarg.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <event.h>
#include <config.h>

struct evbuffer *
      evbuffer_new (void)
  {

    struct evbuffer *buffer;

    buffer = calloc (1, sizeof (struct evbuffer) );

    return (buffer);
  }

void
evbuffer_free (struct evbuffer *buffer)
{
  if (buffer->orig_buffer != NULL)
    free (buffer->orig_buffer);

  free (buffer);
}

/*
 * This is a destructive add.  The data from one buffer moves into
 * the other buffer.
 */

#define SWAP(x,y) do { \
      (x)->buffer = (y)->buffer; \
      (x)->orig_buffer = (y)->orig_buffer; \
      (x)->misalign = (y)->misalign; \
      (x)->totallen = (y)->totallen; \
      (x)->off = (y)->off; \
    } while (0)

int
evbuffer_add_buffer (struct evbuffer *outbuf, struct evbuffer *inbuf)
{
  int res;

  /* Short cut for better performance */

  if (outbuf->off == 0)
    {

      struct evbuffer tmp;
      size_t oldoff = inbuf->off;

      /* Swap them directly */
      SWAP (&tmp, outbuf);
      SWAP (outbuf, inbuf);
      SWAP (inbuf, &tmp);

      /*
       * Optimization comes with a price; we need to notify the
       * buffer if necessary of the changes. oldoff is the amount
       * of data that we transfered from inbuf to outbuf
       */

      if (inbuf->off != oldoff && inbuf->cb != NULL)
        (*inbuf->cb) (inbuf, oldoff, inbuf->off, inbuf->cbarg);

      if (oldoff && outbuf->cb != NULL)
        (*outbuf->cb) (outbuf, 0, oldoff, outbuf->cbarg);

      return (0);
    }

  res = evbuffer_add (outbuf, inbuf->buffer, inbuf->off);

  if (res == 0)
    {
      /* We drain the input buffer on success */
      evbuffer_drain (inbuf, inbuf->off);
    }

  return (res);
}

int
evbuffer_add_vprintf (struct evbuffer *buf, const char *fmt, va_list ap)
{
  char *buffer;
  size_t space;
  size_t oldoff = buf->off;
  int sz;
  va_list aq;

  /* make sure that at least some space is available */
  evbuffer_expand (buf, 64);

  for (;;)
    {
      size_t used = buf->misalign + buf->off;
      buffer = (char *) buf->buffer + buf->off;
      assert (buf->totallen >= used);
      space = buf->totallen - used;

#ifndef va_copy
#define	va_copy(dst, src)	memcpy(&(dst), &(src), sizeof(va_list))
#endif
      va_copy (aq, ap);

#ifdef WIN32
      sz = vsnprintf (buffer, space - 1, fmt, aq);
      buffer[space - 1] = '\0';
#else
      sz = vsnprintf (buffer, space, fmt, aq);
#endif

      va_end (aq);

      if (sz < 0)
        return (-1);

      if ( (unsigned int) sz < space)
        {
          buf->off += sz;

          if (buf->cb != NULL)
            (*buf->cb) (buf, oldoff, buf->off, buf->cbarg);

          return (sz);
        }

      if (evbuffer_expand (buf, sz + 1) == -1)
        return (-1);

    }

  /* NOTREACHED */
}

int
evbuffer_add_printf (struct evbuffer *buf, const char *fmt, ...)
{
  int res = -1;
  va_list ap;

  va_start (ap, fmt);
  res = evbuffer_add_vprintf (buf, fmt, ap);
  va_end (ap);

  return (res);
}

/* Reads data from an event buffer and drains the bytes read */

int
evbuffer_remove (struct evbuffer *buf, void *data, size_t datlen)
{
  size_t nread = datlen;

  if (nread >= buf->off)
    nread = buf->off;

  memcpy (data, buf->buffer, nread);

  evbuffer_drain (buf, nread);

  return (nread);
}

/*
 * Reads a line terminated by either '\r\n', '\n\r' or '\r' or '\n'.
 * The returned buffer needs to be freed by the called.
 */

char *
evbuffer_readline (struct evbuffer *buffer)
{
  u_char *data = EVBUFFER_DATA (buffer);
  size_t len = EVBUFFER_LENGTH (buffer);
  char *line;
  unsigned int i;

  for (i = 0; i < len; i++)
    {
      if (data[i] == '\r' || data[i] == '\n')
        break;
    }

  if (i == len)
    return (NULL);

  if ( (line = malloc (i + 1) ) == NULL)
    {
      fprintf (stderr, "%s: out of memory\n", __func__);
      evbuffer_drain (buffer, i);
      return (NULL);
    }

  memcpy (line, data, i);

  line[i] = '\0';

  /*
   * Some protocols terminate a line with '\r\n', so check for
   * that, too.
   */

  if ( i < len - 1 )
    {
      char fch = data[i], sch = data[i+1];

      /* Drain one more character if needed */

      if ( (sch == '\r' || sch == '\n') && sch != fch )
        i += 1;
    }

  evbuffer_drain (buffer, i + 1);

  return (line);
}

/* Adds data to an event buffer */

static void
evbuffer_align (struct evbuffer *buf)
{
  memmove (buf->orig_buffer, buf->buffer, buf->off);
  buf->buffer = buf->orig_buffer;
  buf->misalign = 0;
}

/* Expands the available space in the event buffer to at least datlen */

int
evbuffer_expand (struct evbuffer *buf, size_t datlen)
{
  size_t need = buf->misalign + buf->off + datlen;

  /* If we can fit all the data, then we don't have to do anything */

  if (buf->totallen >= need)
    return (0);

  /*
   * If the misalignment fulfills our data needs, we just force an
   * alignment to happen.  Afterwards, we have enough space.
   */
  if (buf->misalign >= datlen)
    {
      evbuffer_align (buf);
    }

  else
    {
      void *newbuf;
      size_t length = buf->totallen;

      if (length < 256)
        length = 256;

      while (length < need)
        length <<= 1;

      if (buf->orig_buffer != buf->buffer)
        evbuffer_align (buf);

      if ( (newbuf = realloc (buf->buffer, length) ) == NULL)
        return (-1);

      buf->orig_buffer = buf->buffer = newbuf;

      buf->totallen = length;
    }

  return (0);
}

int
evbuffer_add (struct evbuffer *buf, const void *data, size_t datlen)
{
  size_t need = buf->misalign + buf->off + datlen;
  size_t oldoff = buf->off;

  if (buf->totallen < need)
    {
      if (evbuffer_expand (buf, datlen) == -1)
        return (-1);
    }

  memcpy (buf->buffer + buf->off, data, datlen);

  buf->off += datlen;

  if (datlen && buf->cb != NULL)
    (*buf->cb) (buf, oldoff, buf->off, buf->cbarg);

  return (0);
}

void
evbuffer_drain (struct evbuffer *buf, size_t len)
{
  size_t oldoff = buf->off;

  if (len >= buf->off)
    {
      buf->off = 0;
      buf->buffer = buf->orig_buffer;
      buf->misalign = 0;
      goto done;
    }

  buf->buffer += len;

  buf->misalign += len;

  buf->off -= len;

done:
  /* Tell someone about changes in this buffer */

  if (buf->off != oldoff && buf->cb != NULL)
    (*buf->cb) (buf, oldoff, buf->off, buf->cbarg);

}

/*
 * Reads data from a file descriptor into a buffer.
 */

#define EVBUFFER_MAX_READ	4096

int
evbuffer_read (struct evbuffer *buf, int fd, int howmuch)
{
  u_char *p;
  size_t oldoff = buf->off;
  int n = EVBUFFER_MAX_READ;

#if defined(FIONREAD)
#ifdef WIN32
  unsigned long lng = n;

  if (ioctlsocket (fd, FIONREAD, &lng) == -1 || (n = lng) == 0)
    {
#else

  if (ioctl (fd, FIONREAD, &n) == -1 || n == 0)
    {
#endif
      n = EVBUFFER_MAX_READ;
    }

  else if (n > EVBUFFER_MAX_READ && n > howmuch)
    {
      /*
       * It's possible that a lot of data is available for
       * reading.  We do not want to exhaust resources
       * before the reader has a chance to do something
       * about it.  If the reader does not tell us how much
       * data we should read, we artifically limit it.
       */
      if ( (unsigned int) n > buf->totallen << 2)
        n = buf->totallen << 2;

      if (n < EVBUFFER_MAX_READ)
        n = EVBUFFER_MAX_READ;
    }

#endif
  if (howmuch < 0 || howmuch > n)
    howmuch = n;

  /* If we don't have FIONREAD, we might waste some space here */
  if (evbuffer_expand (buf, howmuch) == -1)
    return (-1);

  /* We can append new data at this point */
  p = buf->buffer + buf->off;

#ifndef WIN32
  n = read (fd, p, howmuch);

#else
  n = recv (fd, (char *) p, howmuch, 0);

#endif
  if (n == -1)
    return (-1);

  if (n == 0)
    return (0);

  buf->off += n;

  /* Tell someone about changes in this buffer */
  if (buf->off != oldoff && buf->cb != NULL)
    (*buf->cb) (buf, oldoff, buf->off, buf->cbarg);

  return (n);
}

int

evbuffer_write (struct evbuffer *buffer, int fd)
{
  int n;

#ifndef WIN32
  n = write (fd, buffer->buffer, buffer->off);
#else
  n = send (fd, (void *) buffer->buffer, buffer->off, 0);
#endif

  if (n == -1)
    return (-1);

  if (n == 0)
    return (0);

  evbuffer_drain (buffer, n);

  return (n);
}

u_char *
evbuffer_find (struct evbuffer *buffer, const u_char *what, size_t len)
{
  u_char *search = buffer->buffer, *end = search + buffer->off;
  u_char *p;

  while (search < end &&
          (p = memchr (search, *what, end - search) ) != NULL)
    {
      if (p + len > end)
        break;

      if (memcmp (p, what, len) == 0)
        return (p);

      search = p + 1;
    }

  return (NULL);
}

void evbuffer_setcb (struct evbuffer *buffer,
                     void (*cb) (struct evbuffer *, size_t, size_t, void *),
                     void *cbarg)
{
  buffer->cb = cb;
  buffer->cbarg = cbarg;
}
